Repair of the mitral and tricuspid valves is a steadily growing and vital part of cardiac surgery. Experience has shown that effecting and maintaining a mitral or tricuspid repair requires a prosthetic annuloplasty ring. A major goal of a ring is to restore the shape of the annulus to its normal geometry. In mitral regurgitation, the annulus often becomes circular. The ring should restore the normal “D” shape. Fully flexible rings or bands do nothing to correct the shape of the pathologic mitral annulus. Only rigid or semi-flexible rings mold the shape of the mitral annulus.
One of the most common causes of a failed valve repair is dehiscence of the ring from the annulus. For the mitral annulus, dehiscence almost invariably occurs along the posterior portion of the ring, since this is the area of the annulus where size reduction and increased stress occurs.